TMS320F28388D: Error interrupt when sending on CAN bus

Nathan Cattin

Hello,

I'm working with the CAN bus and the CAN_A module and I'm able to send and receive messages when using test mode external loopback. Now I want to send messages on the pins, so I juste commented the line CAN_enableTestMode(CANA_BASE, CAN_TEST_EXL).

I was expecting to have an interrupt when message is sent. I have an interrupt but the status value of this interrupt is 0x8000, which means that Error and Status Register value is not 0x07.

Could you help me to understand this error ? What can I verify ?

Thanks a lot,

Nathan

over 5 years ago

0 Joseph Casuga over 5 years ago

TI__Mastermind 40330 points

Hi Nathan,

The loopback test used (can_ex2_loopback_interrupt) is written to use the loopback feature where the transmitted data goes to CAN_TX IO and goes back to the CAN core through the CAN_RX IO into the receive buffer. This will enable a simple CAN transmit-receive handshake using interrupts and without the use of a transceiver to interface to a CAN bus. The transmitted data would still propagate to the CAN_TX pin for observability (in case the frames need to be observed with a scope or a CAN frame analyzer like PCAN...etc..). This external loopback test feature is invoked in function CAN_enableTestMode(CANA_BASE, CAN_TEST_EXL) and commenting this out would unfortunately disable the intent of the test that I described. This would be the reason why CAN_INT register will return a 0x8000 value. You can also check CAN_ES register to see which errors were triggered.

Finally, there are a couple of application notes and training materials that you can check out regarding CAN:

Application report http://www.ti.com/lit/sprace5 has many tested examples. We strongly urge you to look at the Debug tips provided. Most CAN issues can be resolved by going through this checklist.

Application report http://www.ti.com/lit/spracq3 depicts lot of easy to understand waveforms and also provide a tool to introduce error at a chosen bit location.

The TRM chapter explains the CAN protocol implementation in the MCU. i.e. it explains the function of registers/bits. However, it does not explain the protocol itself. For protocol information, refer to these excellent videos:

https://training.ti.com/ti-precision-labs-canlinsbc-can-and-can-fd-protocol?context=1139747-1138099-1139707-1138111

https://training.ti.com/ti-precision-labs-canlinsbc-can-and-can-fd-overview?context=1139747-1138099-1139707-1138109

https://training.ti.com/ti-precision-labs-canlinsbc-can-physical-layer?context=1139747-1138099-1139707-1138110

Here is a list of available CAN books:

https://can-newsletter.org/engineering/engineering-miscellaneous/nr_e_cia_can_books_120529/?utm_source=cmn&utm_medium=email&utm_campaign=cmn-202004

Best regards,

Joseph

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28388D: Error interrupt when sending on CAN bus